I have an XFX nVidia 6600GT overclocked from 500mhz core/1000mhz memory to 550mhz core/1100mhz memory. Runs Half Life 2 on my outdated AMD Athlon XP 2000+ and 384MB RAM with almost no problems whatsoever (it goes to about 5-10 fps for the first 5-6 seconds after it loads, and then goes to 30+fps, but that's just because of my low amount of ram).